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Full text of "Alaskan glacier studies of the National Geographic Society in the Yakutat Bay, Prince William Sound and lower Copper River regions"

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of the glacier in 1908 and again in June, 1910. On one photograph of the 1910 ice cliff from Schrader's site, we have indicated by an ink line the amount of advance'between 1907 and 1910. This, however, shows only the lobe which retreated 1700 feet between 1900 and 1907, for the lobe which advanced 4000 feet is not seen in the picture because it is hidden behind the nearer lobe, having retreated farther before the recent advance.
There was slight additional advance of the ice cliff in the lake during the time of our visit in the summer of 1910, when between June and August the advance amounted ta 100 feet. The southern glacier margin was crevassed and advancing in August, 1910, and the northern margin, which was also advancing in August, 1910, showed an appreciable forward movement between the times we photographed it in 1909 and 1910.
The retreat from 1888 to 1008 and the subsequent advance are summarized in the following table. The possible error in any given map would modify these amounts only slightly.
Date	Distance from Site of Railway Bridge	Change in	Amount	Based upon Observations by
	to Ice Cliff	Glacier		
After 1885 and be-				
fore 1888	400 feet	Advance		Henry T. Allen l
October,       1900	7,900 feet	Retreat	7,500 feet	D. C. Witherspoon
Fall,             1905	8,250 feet	Retreat	350 feet	Railway engineers
Summer,      1906	11,880 feet	Retreat	3,630 feet	«           «
Summer,      1908	13,500 feet	Retreat	1,620 feet	«                            (C
June,             1910	9,500 feet	Advance	4,000 feet	«                            (C
August,        1910	9,400 feet	Advance	100 feet	Martin
During the advance in 1909 and 1910 the form of the ice cliff changed in detail (Fig. 65), though it is reported that twice as many icebergs were discharged in 1908, when the-glacier was retreating, as in 1909, when it advanced.* One remarkable feature was the shifting of position of the salient ice point. There were also pronounced changes in the capes and coves of the ice cliff between June and August, 1910.
The most striking change was the detaching of huge masses from the glacier, one near the northern, the other near the southern margin of the ice cliff. These were not icebergs but large areas of the glacier itself, and their separation from a glacier which was advancing rather than retreating was an unusual circumstance.
About the middle of July, 1909, a section of Miles Glacier at least half a mile square, became separated and is said to have floated out into the lake, where the mass collapsed and broke up into icebergs which completely filled the lake. This was near the northern, end of the ice cliff. It took place before our visit in 1909 and we have this information^
i Date 1885 from Allen.  .Date 1888 from ages of trees as determined in 1910. »Based on a count by A. 0. Johnson at the railway bridge.